Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1887-12-13
PERoNOSPORA VITlC0LA.
Is This Vine Fungus tthe BLACK Rot :
or a. DnMny NIildenr ,,l in CaIifnrria

Is This Vine Fungus tthe "BIacI Rot
or Downy Mildew ~ in California.
DR.. H. W, Harkness, President of the.
Academy of Sciences, San Francisco, sends
the following communication to the But
leti'a, and which will be of interest to vine
growers;
Your paper Of a recent date contains a
! letter from Professor +. L. Scribner, Mvcol-
ogist OF the United States Agricultural
department at Washington, in which he
denles that either back-rot (PhysaIos-
pOrd Btdtceliii) or the " "downv miidewp
! (Fef0nosporG ritic0tG) occurs in California,
| ana warns against Introduction from with
ont. With respect to the former of these, /
nave nothing TO add, no specimen from
TINS coast ever having reached me; in re-
gard 10 tha latter there is unfortunately
for us, no donbt that Mr. Scribner is wrong.
The tact that our wild grape-vines, in
close proximity 10 vineyards, have been
found infested with this most dangerous
fungus has been often alluded to by me,
and warning given as to the danger Of in
fiction.
The Importance of the matter to the vel
fare OF the vineyards of the State seemed so
pressing that paper on the subject illus
trated by stereopticon slides, was read by
| the writer before the California Academy of
Sciences June 18th of this year
1t is 10 be regretted that professor Scrib-
ner did not make more c,reful inquiry
before issuing bis statement proof to the
| contrary being directly available as may be
seen from the following extract from Fungi
OF the Pacific Coast, No. 8, in Bulletin Cali
fornia Academy of Sciences, No. !, issued
June, 1887:
"Peronosp0ra Vaico'a, B. & Con living
leaves of VHiS CdlforRicG, near Bartlett
Springs. Lake county, June, 1884, and Rus
sian river, June, 1856. 1906, 4128.
This fungus, forming large white
patches, is confined to the lower surface of
the leaf, where only the stomata from
which it emerges is found. The core
spending part OF the upper surface is mach
paler than the healthy portion of the leaf,
on which account it is noticeable to g con-
siderable distance. In both the cases noted
above 1t is very abundant aud is a menace
to our vineyards not TO be lightly regarded.
1t was first observed by the writer in
| 1872 in vineyard near Sacramento, which
has since, the vines having been uprooted,
been devoted to other uses. The vineyard
| was near the levee and in close proximity
| TO wild grape vines, from which the fungus
was undoubtedly derived.
" PerOROSp0ro uiticOLG is not likely to prove
injurious in the Northern States. but in
California the climate and conditions are
similar to those of France and Italy, in
| which countries it does great damage. 1t
appears with us On the wild vine at the
time of Towering and rObs it Of the leaves
| necessary TO shield the growing grapes
from the scorChing rays of the sun.
Su 'pL ur,ng, wa, hes and all such rem
edies, used with more or less success in
various fungoid diseases of the vine, are
necessarily useless in this, for the resting
spore by which it propagates in the sue
ceeding year is formed deep in the sub
stance of the leaf and only becomes free by
its decay.
Vineyards in the vicinity of infested
wild vines will sooner or later acquire it
from them and the experience of the cof-
fee plantations OF Ceylon will be repeated.
These became infected by a fungus proba-
ably infrequent on the original host, which
propagated itself to such an extent on the
| more fertile one as almost to ruin the plant
ers.
"The only efectual remedy which can
| be suggested is 10 destroy by fire the in
fected vines taking care that 10 leaves
| escape; and where vineyard is to be
planted in the vicinity OF wild vines it
| would be well to destroy the latter, as
measure of precautiOn."
The letter of mir. SGrbner will do great
harm if it leads our viticult urists to disre-
! gard an imminent danger already in our
| midst while trying to protect themselves
from importation without.